Among all the data storage solutions, the optical disks are becoming more and more important for backing up data and exchanging information because the optical disks have many advantages including a high storage capacity, easy to handle and carry, and a long preserving time for the stored data. Till now, the optical disk drives can be found all around such as in desktop computers, laptop computers, DVD players, and even some instruments or electronic products with built-in microprocessors.
Referring to FIGS. 1 and 2, perspective and exploded views of a conventional optical disk drive are shown to include a lower casing half 2, an upper casing half 6 coupled to the lower casing half 2 to form a casing 1, a chassis 4 disposed within the casing 1 for carrying a pick-up head thereon, a front panel 3 fixed to and covering the front open end of the casing 1, and a disk tray 5 disposed within the casing 1 above the chassis 4.
Referring to FIGS. 3 and 4, top and perspective views of the lower casing half 2 are shown to include a gear transmission system 10 for driving the disk tray 5 (see FIG. 2) between an extended position, in which, the disk tray 5 extends outwardly from the casing 1 via an entrance-and-exit slot formed through the front panel 3, and a retracted position, in which, the disk tray 5 retracts inwardly into the casing 1 via the entrance-and-exit slot. The gear transmission system 10 includes a first gear 12, a gear transmission unit 101, and a driving plate 13. The first gear 12 is disposed within the lower casing half 2. The gear transmission unit 101 includes a driving motor 11, a second gear 14 fixed co-axially on an output shaft of the driving motor 11, and a third gear 15 coupled to the second gear 14 via a plurality of transmission gears in such a manner that rotation of the second and third gears 14, 15 results in movement of the disk tray 5 between the extended and retracted positions. The driving plate 13 is disposed within the lower casing half 2 and extends in a transverse direction relative to a longitudinal axis of the lower casing half 2. The driving plate 13 is movable along the transverse direction to left and right sides of the lower casing half 2 (see FIGS. 4 and 5). The driving plate 13 has a right serrated portion 131 meshed with the first gear 12, and a left serrated portion 132 disposed adjacent to and facing the third gear 15. The third gear 15 is further operably associated with the disk tray 5 in such a manner that rotation of the third gear 15 in clockwise and anti-clockwise directions alternately results in movement of the disk tray 5 to the retracted and the extended positions and movement of the driving plate 13 to the left and right sides of the lower casing half 2.
When the disk tray 5 is in the extended position (not shown), the driving plate 13 is moved to the left side of the lower casing half 2, the first end 1311 of the right serrated portion 131 is meshed with the first end 121 of the first gear 12, and the first end 1321 of the left serrated portion 132 is not engaged with the third gear 15 (see FIGS. 3, 4 and 7A). In the same manner, when the disk tray 5 is in the retracted position (not shown), the driving plate 13 is moved to the right side of the lower casing half 2, the second end 1312 of the right serrated portion 131 is meshed with the second end 122 of the first gear 12, and the second end 1322 of the left serrated portion 132 is engaged with the third gear 15 (see FIGS. 5, 6 and 7A).
In the aforesaid conventional disk drive, the left serrated portion 132 is not constantly meshed with the third gear 15. The left serrated portion 132 is started to engage with the third gear 15 in the midway of the inletting process of the disk tray 5 so that the engagement between the first end 1321 and the third gear 15 could be improper. Thus, jamming of the left serrated portion 132 with respect to the third gear 15 may occur. Moreover, after completing inletting process of the disk tray 5, the second end 1322 of the left serrated portion 132 is engaged with the third gear 15, the third gear 15 would apply a force on the second end 1322 which may cause the broken of the tooth of the second end 1322.